Carboazirenes



United States Patent 3,497,351 CARBOAZIRENES George R. Harvey, Kirkwood, Mo., assignor to Monsanto Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed Dec. 29, 1965, Ser. No. 517,438 Int. Cl. C07d 23/00; B01j 1/10 US. Cl. 260239 Claims ABSTRACT OF THE DISCLOSURE Compounds of the formula R" 0 RCH J: u

wherein R is hydrogen, alkyl up to 4 carbon atoms or phenyl; R" is alkyl up to 4 carbon atoms, hydrogen, phenyl or benzyl; and R is alkyl up to 12 carbon atoms, alkoxy up to 12 carbon atoms, amino, monoalkylamino up to 4 carbon atoms, dialkylamino where alkyl is up to 4 carbon atoms, the aromatic radicals of phenyl, phenoxy, benzyl or benzoxy and substituted radicals where the substituent is alkyl up to 4 carbon atoms, alkoxy up to 4 carbon atoms, chlorine, bromine or nitro.

The compounds are prepared by the irradiation of conjugated vinyl azides with ultra-violet light in the range of 200 to 300 111,11.

These compounds are useful in inhibiting the growth of fungus.

This invention relates to a new class of chemical compounds and a novel procedure for their preparation. More specifically, the invention is directed to the preparation of chemicals useful in inhibiting the growth of fungus.

It has been found that the ultraviolet irradiation of conugated vinyl azides will induce a rearrangement to the azirene structure. The useful conjugated vinyl azides are described and claimed in copending application Ser.,

No. 517,488, filed Dec. 29, 1965, by George R. Harvey. The novel reaction by which the new compounds are formed follows the equation:

wherein R' is selected from the class consisting of hydrogen, alkyl of up to four carbon atoms and phenyl; wherein R" is selected from the class consisting of alkyl of up to four carbon atoms, hydrogen, phenyl and benzyl; and wherein R is selected from the class consisting of alkyl of up to twelve carbon atoms, alkoxy of up to twelve carbon atoms, amino monoalkylamino wherein tthe alkyl moiety has up to four carbon atoms, dialkylamino wherein both alkyl moieties have up to four carbon atoms; the aromatic radicals consisting of phenyl, phenoxy, benzyl, benzoxy, and the said radicals containing substituents selected from the class consisting of alkyl of up to four carbon atoms, alkoxy of up to four carbon atoms, chlorine, bromine and nitro.

The irradiation of conjugated vinyl azides to form the claimed azirenes requires the use of ultraviolet light of a specific wavelength, characteristic of the light emitted by a low pressure mrecury lamp. The most effective wavelength of light is 253 mu (millimicrons) but light of higher and lower ma values can be used. The suitable ultraviolet light has a wavelength between 200 mg and 300 mu. In effecting the useful reaction, nitrogen is evolved and this evaluation can be used in estimating the progress of the reaction. When the vinyl azides are irradiated with the proper wavelength of ultraviolet light the rearrangement reaction is substantially complete when the evolution of nitrogen subsides.

The reaction can be most effectively accomplished by dissolving vinyl azides in an inert solvent, such as benzene, toluene, xylene, pentane, cyclohexane, diethyl ether, petroleum ether, octane and other aromatic and aliphatic solvents. The hydrocarbons are especially useful media for conducting the reaction. The resulting azirene is readily separated by evaporating the solvent medium and distilling the concentrated residue.

Further details in the preparation of the described azirene derivatives are set forth in the following examples.

EXAMPLE 1 Ethyl B-azidocrotonate (2.60 g., 16.8 mole) dissolved in 100 ml. of benzene was photolyzed with a low pressure mercury lamp at 253 m for 18 hours when nitrogen evolution was complete. The solution was concen- 'trated and distilled at 30 C./0.l mm. to separate 2.0 g. (93%) of a light yellow oil. This oil had strong absorption in the infrared at 4.85;]. (ketenimine) and 5.82 1. and showed two components on G.L.C. (SE 30, in the ratio 321. When this oil was redistilled at 8090 C./ 70 mm. the ketenimine band disappeared from the infrared spectrum and the mnior component was not present in the chromatogram. The azirene has infrared maxima at 115.85 and 8.4 with a small peak at 5.6 1 (azirene). The nmr spectrum has signals at 2.2 (one proton spike) and 2.456 (methyl spike). The mass spectrum has a major fragment at 54 m/e Analysis.--Calcd. for C H NO C, 56.68; H, 7.14; N, 11.02. Found: C, 56.79; H, 7.30; N, 10.90.

This compound was identified as 3-methyl-2-carbethoxy-2H-azirene.

EXAMPLE 2 Nine grams of ethyl ,e-azido-a-methylcrotonate was irradiated as a 10% solution in benzene for 24 hours with a low pressure mercury lamp at 2.53 me. The solution was concentrated and distilled at 95 C./ 32 mm. to s parate 5 g. of azirene. The oil had infrared absorption at 5.7a corresponding to the azirene double bond stretch. The mass spectrum was consistent with this structure.

Analysis.Calcd. for C H NO C, 59.60; H, 7.80; N, 9.94; M.W., 141. Found: C, 59.43; H, 8.01; N, 9.75; M.W., 143.

This compound was identified at 2,3-dimethyl-2-carboethoxy-ZH-azirene.

EXAMPLE 3 The irradiation of fl-azidocrotonamide by the procedure of Example 1 produced a compound identified as 3- methyl-2-carbamide-ZH-azirene.

EXAMPLE 4 fi-Azido-N-methylcrotonamide in benzene solution was irradiated by light of approximately 253 III/L from a low pressure mercury vapor lamp. After 24 hours the nitrogen evolution had ceased. The reaction mixture was concentrated by evaporation of the solvent medium and the residue distilled. The product recovered was identified as 3-methyl-2- (N-methylcarbamide) -2H-azirene.

EXAMPLE 5 A compound identified as 3-methyl-2-carbobenzoxy- 2H-azirene was prepared by irradiating p-chlorobenzyl (i-azidocrotonate by the procedure of Example 1.

3 EXAMPLE 6 A chlorobenzene solution of p-nitrophenyl fi-azidocrotonate Was irradiated with ultraviolet light of 200 to 300 mu for 30 hours. The resulting reaction mixture was topped to remove the residue distilled to recover 3-methyl-2-carbo-p-nitrophenoxy-ZH-azirene.

EXAMPLE 7 2 ethyl-3-methyl 2 carb-3',4'-dibromophenoxy- 2H-azirene was prepared by the procedure of Example 6 except that it involved the irradiation of 3,4-dibromophenyl fl-azido-u-ethylcrotonate.

EXAMPLE 8 A petroleum ether solution of fi-azido fi-ethylacrylamide was irradiated with ultraviolet light m 253. When the nitrogen evolution ceased the petroleum ether was evaporated and the residue distilled. The product recovered was identified as 3-ethyl-2-carbamido-ZH-azirene.

EXAMPLE 9 A diethyl ether solution of fl-azido-N-ethylcrotonamide was irradiated by the procedure of Example 1. By evaporation of the solvent medium a product was recovered by distillation and identified as 3-methyl-(N-ethylcarbamido) -2H-azirene EXAMPLE 10 The procedure of Example 9 Was repeated except the compound subjected to irradiation was dodecyloxy t3- azido B-ethylacrylate. The resulting compound was 3- methyl-Z-carbododecyloxy-ZH-azirene.

EXAMPLE 11 Using the procedure of Example 1 ethyl fi-azido-aphenylbutadienoate was dissolved in ether and irradiated wtih an ultraviolet lamp m 253. After the nitrogen evolution was complete the remaining ether was evaporated and the compound formed was identified as having the formula EXAMPLE 12 Methyl 4-pheny1-3-azidocrotonate was prepared by reacting sodium azide with the methyl ester of 3-benzyl-2, 3-butadienoic acid. The subject compound was irradiated by the procedure of Example 1 with ultraviolet light to form 3-benzyl-2-carbomethoxy-2H-azirene.

EXAMPLE 13 Propadienylbenzophenone was dissolved in acetone and treated with sodium azide. The resulting ,B-azidopropyl benzophenone was dissolved in cyclohexane and irradiated with ultraviolet light. The product recovered from the reaction mixture was identified as having the formula EXAMPLE 14 Propadienyl ethyl ketone' was dissolved in tetrahydrofuran and a mole equivalent of sodium azide was added thereto. The reaction product was dissolved in petroleum ether and the resulting solution irradiated with light from a low pressure mercury lamp. The product recovered from the reaction mixture was dentified as 2-propionyl-ZH-azirene.

- EXAMPLE 15 A toluene solution of p-ethylphenyl l3-azidocrotonate was irradiated with ultraviolet light from a low pressure mercury lamp. By continuing the treatment until the nitrogen evolution subsided a substantial yield of 3-methyl-Z-carbo (p-ethoxyphenyl)-2H-azirene was recovered,

EXAMPLE 16 Using the procedure of Example 1, 2-azidoallyl p-nitrophenone was treated with ultraviolet light (253 mp.) until nitrogen evolution ceased. The reaction mixture was distilled and the product recovered was identified as 3- methyl-Z-carbo(p-nitrophenyl)-2H-azirene.

EXAMPLE 17 wherein R is selected from the class consisting of hydrogen, alkyl having up to four carbon atoms, and phenyl; wherein R" is selected from the class consisting of hydrogen, alkyl of up to four carbon atoms, phenyl and benzyl; and wherein R is selected from the class consisting of alkyl having up to twelve carbon atoms, alkoxy having up to twelve atoms, amino, monoalkylamino in which the alkyl moiety has up to four carbon atoms, dialkylamino wherein each alkyl moiety has up to four carbon atoms, the aromatic radicals of the class consisting of phenyl, phenoxy, benzyl, benzoxy and the said aromatic radicals containing substituents selected from the class consisting of alkyl of up to four carbon atoms, chlorine, bromine and nitro.

2. A compound of claim 1 which is 2-carboethoxy-3- methyI-ZH-azirene.

3. A compound of claim 1 which is 2,3-dimethyl-2- ethoxy-2H-azirene.

4. A compound of claim 1 which is 2-carbamido-3- methyI-ZH-azirene.

5. A compound of claim 1 which is 2-methyl-2-carbamido-3-methyl-2Hazirene.

References Cited UNITED STATES PATENTS 6/1966 Cleaver 260239 12/1967 Cotter 260-239 OTHER REFERENCES Burger, Medicinal Chemistry, (New York, 1960), pp. 1050-1051.

ALTON D. ROLLINS, Primary Examiner U.S. Cl. X.R. 

